The Egypt international Mohamed Salah has joined Chelsea from the Swiss club Basel. Photograph: Action Press/Rex Features

Chelsea have moved swiftly to secure a replacement for the departing Juan Mata by deflecting strong interest from Liverpool to sign the highly rated winger, Mohamed Salah, from Basel.

The Egypt international will cost an initial £12m which could rise to £16m with the move subject to the player agreeing personal terms and passing a medical. The 21-year-old, who boasts an impressive 17 goals in 27 games for his country, is likely to be introduced to the crowd at Sunday's FA Cup fourth-round tie against Stoke City when Chelsea's other major mid-season signing, Nemanja Matic, will hope to make his first start in his second spell at the club.

Salah will bolster attacking ranks that have been weakened by the sales of Mata, who should complete his £37m move to Manchester United by the weekend, and Kevin de Bruyne, the latter having joined Wolfsburg for £16.5m earlier this month.

While the Belgian was a peripheral figure at the club with all parties accepting a move was timely as he sought to secure regular first-team football ahead of the World Cup, Chelsea's support are still digesting the departure of Mata, their team's player of the season in each of the previous two campaigns. José Mourinho will address the issue publicly in his pre-match press conference on Friday, and is expected to confirm a bid the size of that lodged by United simply could not go ignored, with the arrival of the talented Salah offering some measure of appeasement.

The Egyptian has scored in his last three games for Basel against Chelsea, including in both the Swiss team's Champions League group matches between the sides earlier this season, and is expected to sign a contract running to 2019. Those goal rewards have not been typical of domestic form, where the quality of the winger's performances has fluctuated, but Mourinho has spied enough potential in Salah to target him as a talented squad player with a bright future in the game.

A statement released by the club said: "Chelsea can confirm an agreement has been reached with FC Basel for the transfer of their 21-year-old attacking midfielder Mohamed Salah. The move is subject to the Egyptian international agreeing personal terms and completing a medical examination."

The winger can operate on either flank, exposing both Ashley Cole and Branislav Ivanovic for periods in those contests this term, and is quick across the turf even if he has lacked consistency in delivery and in front of goal. As a youngster of obvious raw talent, Chelsea will still consider his signing something of a coup.

Liverpool were one of a number of Premier League clubs to have scouted the forward extensively and had hoped to add him to their ranks, initially as an impact player most likely to be used from the bench in tight contests. Yet they had only considered him worth in the region of an initial £8m at most and have found themselves gazumped by Chelsea, as they were for the Brazilian winger Willian, who had also attracted interest from Tottenham Hotspur, back in August.

Salah had moved to Switzerland from the Egyptian side Al Mokawloon in the summer of 2012 and went on to score five league goals in 29 appearances as Murat Yakin's side claimed a fourth successive domestic title. He departs the club top of the table yet again to become the third new arrival at Stamford Bridge this month after Matic and the young Burkina Faso winger, Bertrand Traoré, who has since been loaned to Vitesse Arnhem. The veteran midfielder Michael Essien is also expected to depart before the closure of the window.